nelson mandela. tomorrows memorial service will serve as a rare reunion of nearly all of the living american presidents. kpix5 is in the news room now and the number of dig any tar its i imagine is giving south african police quite a security challenge. >> reporter: yes, frank. more than 80,000 mourners are expected to attend the memorial and thousands of police officers will be on hand and right now a memorial outside nelson mandela's former home is growing as well as a crowd of south africans who have come together since his death. >> police are preparing today for a memorial service for nelson mandela at a soccer stadium tomorrow. president obama leaves this morning for south africa where he will attend the massive public memorial. former presidents bush, clinton and carter will also be in attendance along with more than 50 heads of state, making it one of the largest gatherings the world leaders in recent history. >> this is a test for us. >> the head of south africa's national defense force says